Image sticking is considered as one of serious problems in manufacture process of a Thin Film Transistor-Liquid Crystal Display (TFT-LCD). The image sticking can be classified into Direct Current (DC) image sticking and Alternating Current (AC) image sticking. Generally, the DC image sticking is regarded as an image sticking caused in the following manner: mental particles and non-mental particles originally being in a free state in a liquid crystal layer run to one side of an electric field due to asymmetry of driving voltages of the TFT-LCD, and then fail to return to the free state when no voltage is applied, and thus differences in brightness of the TFT-LCD may be caused, resulting in the image sticking.
The driving voltages of TFT-LCD for respective gray scales comprise a high driving voltage and a low driving voltage, and the driving voltages of the TFT-LCD are determined generally according to a relationship curve between driving voltages of a source driving integrated circuit and light transmittances of the TFT-LCD as shown in FIG. 1 and a Gamma curve of the source driving integrated circuit as shown in FIG. 2. Wherein, the source driving integrated circuit is a circuit for driving a display module of the TFT-LCD. The Gamma curve is a curve reflecting a relationship between the light transmittances of the TFT-LCD and the gray scales, and may be determined according to a Gamma value of the TFT-LCD. Each TFT-LCD has a fixed Gamma value usually, and the Gamma value is a specified value leading to a distortion to an input image by the TFT-LCD. If the Gamma value of the TFT-LCD is 2.5, given a light brightness of 0.5 for a pixel, the light brightness output on a display is only 0.2 (that is, 0.5/2.5) in a case that no color management application is performed. Different Gamma values correspond to different Gamma curves, and in the curve shown in FIG. 1, horizontal ordinates represent the driving voltages of the source driving integrated circuit, and vertical ordinates represent the light transmittances of the TFT-LCD; in the Gamma curve shown in FIG. 2, horizontal ordinates represent gray scale levels, and vertical ordinates represent the light transmittances of the TFT-LCD. Change in the driving voltage may lead to change in the gray scales of the TFT-LCD, and in turn the change in the gray scales may lead to change in the light transmittance of the TFT-LCD. Therefore the driving voltage corresponding to each gray scale may be determined by a manner that the correspondence between the gray scales and the light transmittances of the TFT-LCD is determined at first, and then the correspondence between the light transmittances of the TFT-LCD and the driving voltages is determined. Such method for determining the driving voltages is embodied as: the light transmittance of the TFT-LCD for each of the respective gray scales in the Gamma curve of the TFT-LCD is determined at first, then the larger one of two voltages, which correspond to the light transmittance of the TFT-LCD for the gray scale, on the relationship curve between the driving voltages of the source driving integrated circuit and the light transmittances of the TFT-LCD is the high driving voltage of the gray scale, and the smaller one is the low driving voltage of the gray scale. Generally, in the source driving integrated circuit, a voltage jump may appear at a pixel electrode due to a coupling capacitor between a gate and a source of TFT at a moment when a gate signal becomes off from on, and a difference of the voltages at the pixel electrode before and after such jump is referred to as a voltage jump. There is also a reference voltage Vcom in the source driving integrated circuit of the TFT-LCD, and a voltage difference between the reference voltage Vcom and the driving voltages may cause a difference in an angle of deflection of the liquid crystal molecules, such that the light transmittances are different. The reference voltage Vcom may be determined according to the driving voltages as the gray scale is 0. During display, the driving voltages of the TFT-LCD would be symmetrical if the voltage jump of the pixel electrode for each gray scale is the difference between an average of the high driving voltage and the low driving voltage of the gray scale and the reference voltage Vcom. However, the voltage jump of the pixel electrode is often different from the difference between the average of the high driving voltage and the low driving voltage of the gray scale and the reference voltage Vcom in an actual circuit, such that the driving voltages of the TFT-LCD are asymmetrical in an actual usage and the image sticking would occur.